Celebrating in South Carolina on Saturday night, Newt Gingrich said his victory proved "people powered with the right ideas beats big money."

Paul SancyaAP

Newt Gingrich has beaten Mitt Romney in South Carolina. The question now becomes whether he can pull off that trick enough times in enough states to deny Romney the Republican presidential nomination.

It was a big win for Gingrich, the former House speaker, who took 40 percent of the vote, compared to 28 percent for Romney, a former Massachusetts governor.

"Thank you to everyone in South Carolina who decided to be with us in changing Washington," Gingrich told a crowded ballroom of supporters in Columbia. "The biggest thing that I take from the campaign in South Carolina is that it is very humbling and very sobering to have so many people who want so deeply to have their country get back on the right track."

Gingrich's victory represents a dramatic turn in the race. Just days ago, it appeared that Romney would coast to a double-digit win in South Carolina. A victory there might have put the race out of reach of other contenders, all but assuring Romney the nomination.

Instead, the campaign will become even more heated as attention turns to the Florida primary on Jan. 31. And it appears that Gingrich has, at long last, united the "anti-Romney" vote behind one candidate.

"I do believe that a number of the people who are looking for a choice other than Romney will probably recognize now that if it's going to be anybody, it's going to be Newt," says Curt Kiser, a longtime former legislative leader in Florida.

"It's a two-man race and it's going to be very hotly contested," he says.

Gingrich's Resurrection

The results in South Carolina Saturday represent an amazing comeback for Gingrich. His campaign appeared moribund last June, when the bulk of his campaign staff quit en masse.

He leapt to the top of the polls in November, only to have his support seriously eroded by a volley of attack ads launched by a superPAC supporting Romney.

Gingrich finished a distant fourth in both the Iowa caucuses and New Hampshire's first-in-the-nation primary. But his pugnacious performances in the two South Carolina debates this week served to energize many South Carolina conservatives.

"We had poll data every night and Romney was ahead every night until Tuesday," says David Woodard of Clemson University, referring to Clemson's Palmetto Poll. "That clearly had to be the debate [Monday]."

Indeed, the AP reports that about half of South Carolina voters surveyed in exit polls on Saturday said the debates played a "major role" in their decision-making.

The standing ovation Gingrich won at the debate on Monday was unprecedented in the memory of most longtime political observers. But he repeated the trick on Thursday, winning over the crowd with his attack on debate moderator John King of CNN for asking him about complaints lodged by one of his ex-wives that he had asked for an open marriage.

"What they saw from Newt Gingrich in the debates was some fight," South Carolina Sen. Jim DeMint, a Republican who stayed neutral in the race, told NPR's Audie Cornish. "They want to be sure the next president is willing to take on some very powerful forces."

Anti-Romney Forces

Romney had been able to slough off complaints from Gingrich that, as chief of Bain Capital, he had been responsible for thousands of people losing their jobs.

But Romney's personal finances proved to be a more salient issue. His refusal to release his income tax returns and revelations that millions of his own dollars have been invested offshore have been troubling to some voters, says Jim Guth, a political scientist at Furman University in Greenville, S.C.

"They raised some doubts and gave a lot of marginal Romney people reason for thinking about some of the other candidates," Guth says. "One way or the other, those things haven't helped."

Romney himself sought to address the matter in his concession speech Saturday, saying that Republicans who sought to criticize his business record or free enterprise in general would not be "fit" to be the party's nominee.

"Those who pick up the weapons of the left will find them turned against them tomorrow," Romney said.

The Road Ahead

Romney has enjoyed a sizable lead in polls in Florida, which will be the next state to vote on Jan. 31. But that lead — like his advantage in South Carolina — could evaporate quickly. The race has remained remarkably fluid.

Many observers believe that Romney has the organization — and the money — to prevail over the course of what may be a long nomination fight that will quickly spread to many more states.

Early voting is already underway in Florida and the Romney campaign has been aggressive about getting its supporters to the polls early — and in droves.

"He's got the organization," says Pete Dunbar, a GOP consultant in Florida who is not aligned with any of the presidential campaigns. "One of the thing I noticed today is that the Romney organization had people going in groups to vote here in Florida."

Romney also plans to push back hard against Gingrich, calling on him to explain his consulting work for mortgage giant Freddie Mac. On Saturday, Romney's campaign sent a cake to Gingrich's South Carolina headquarters to mark the 15th anniversary of the House vote reprimanding Gingrich for ethical violations.

Romney supporters said that his campaign has always been prepared to run a marathon.

Winning Iowa or South Carolina would have been a welcome bonus, but the campaign's hope all along for the month of January rested on winning New Hampshire and Florida, former Minnesota Gov. Tim Pawlenty, a Romney campaign co-chairman, suggested to NPR's Guy Raz.

"He has the only campaign built to go the distance," Pawlenty said.

'A Long Hard Slog'

Former Pennsylvania Sen. Rick Santorum wasn't able to capitalize on the fact that he was able to come from the back of the pack to tie Romney in the Iowa caucuses, the year's first GOP nominating contest. He finished fifth in New Hampshire and, despite having won the support of a group of prominent evangelical leaders last weekend, finished a distant third in South Carolina, with 18 percent.

"Endorsements just don't matter unless they can be backed up with some money," says Clemson University's Woodard, who is a GOP consultant but not working for any of the presidential hopefuls.

There had been speculation that Santorum would drop out if he fared poorly in South Carolina. But he vowed to press on.

"It's a wide open race," Santorum said to supporters gathered at The Citadel Saturday. "Join the fight."

Fourth-place finisher Ron Paul, a Texas congressman, also pledged to keep campaigning in Florida and beyond.

Paul told his supporters Saturday that the first three states to vote would only award 37 delegates between them — less than 2 percent of the total.

"This is the beginning of a long hard slog," he said. "We will continue to do this."

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